Electric switch



July 17, 1951 R. K. BYOYER 2,560,717

ELECTRIC sun-ca Filed Nov. 15, 1950 mvzwrox lFuPH A. Boys/g By We, 7 m, J

Arm/V476 Patented July 11, 1951 2,560,717

UNITED STATES PATENT OFFICE ELECTRIC SWITCH Ralph K. Boyer, Lakewood, Ohio, assignor to The Dill Manufacturing Company, Cleveland, Ohio, a corporation of Ohio Application November 15, 1950, Serial No. 195,888

9 Claims. (Cl. 200-152) The present invention relates to an electric switch of the type in which a body of mercury is employed for the purpose of making or breaking contact with electric terminals which are adapted to be included in an electric system.

This application is a continuation in part of my application, Serial No. 82,822, filed March 22, 1949, now abandoned.

Basically, the switch forming the present invention employs the principle that a globule or a body of mercury will when unrestrained and supported by a relatively plane surface, assume globular form and retain such form. This physically is due to the cohesion between the molecules forming the body of the mercury and to the fact that there is a surface tension in the outer surface of the globule, both of which forces tend to preserve the identity or discrete character of the globule of mercury.

More specifically, the invention comprises a switch in which there are spaced electric terminals between which there is a globule of mercury which when unrestrained or, in other words,-

free from outside influences will not span the distance between the terminals, but when the globule is by pressure deformed in such a way as would tend, as it were, to flatten the globule of mercury, it will while maintaining its discrete integral identity be extended so as to be in contact with the electric terminals before mentioned and in such situation be available as a transmitter of an electric current between the terminals.

Reference should be made to the accompanying drawings forming a part of the disclosure of this invention in which,

Fig. 1 is a top plan view of one form of the invention.

Fig. 2 is a section upon the line 2-2 of Fig. 1.

Fig. 3 is similar to Fig. 2 but showing a member of the switch in a different position from that in Fig. 2 and also showing an operating means.

Fig. 4 is a top plan view of a modified form of the invention.

Fig. 5 is a section upon the line 5-5 of Fig. 4, and

Fig. 6 is a similar to Fig. 5 showing the elements of the switch in a position differing from that in Fig. 5.

Basically, the switch comprises two members which in 2 are indicated at I and 2 respectively. These two members I and 2 are associated with each other in such a manner that there is a chamber 3 formed between them. This chamber may properly be called a closed chamber in that it is self-contained and not opened to the atmosphere. The member I has openings 4 and 4a which are occupied by electric terminal members 5 and 5a. The association of the terminals 5 and 5a with the openings 4 and 4a is a close fitting one so that there is no opening to the atmosphere because of the employment of the opening 4 and 4a.

The member 2 in the present instance is secured to the member I at the peripheral portion thereof by the flange 6. The member 2 is made of material which is flexible and is of such a gauge that when formed with the dished portion 2:42, the same may be moved to the position shown in Fig. 3, thereby reducing the volumetric capacity of the chamber, this movement being accomplished by the application of a force either by the hand or by some mechanical or other power means as clearly indicated in Fig. 3. When the pressure which has been applied in the manner before indicated i withdrawn, the inherent resiliency of the member 2 causes it to return to its initial position which, as before indicated, is that illustrated in Fig. 2 of the drawing.

The member 2 may be properly described as a diaphragm with a portion which is capable of being moved and with inherent resiliency suflicient toreturn it to its initial position when an extraneous force is relieved.

Preferably that portion of the member I which is adjacent to the member 2 is slightly dished and also preferably the member 2 in the portion 2:: is slightly dished in the region which is opposite to the dished portion of the member I. This provides a chamber in which in the position shown in Fig. 2 of the drawing the central portion is of greater depth or width than toward the margin of the chamber.

Within the chamber is a body of mercury in discrete globular form which is indicated at I. This body of mercury, when the switch is in horizontal position, will assume essentially the position which is shown in Fig. 2. The body of mercury is of lesser volume than that of the said chamber. Obviously, if the members I and 2 are arranged in vertical position the body of mercury 1 may by gravity be influenced into a position nearer the limiting periphery of the chamber, but

the discrete character of the globule of mercury is still maintained.

Because of the inherent physical characteristics of a globule of mercury such as indicated at I, it does not spread but instead maintains its body identity or discrete character when the substance, be it metal or otherwise, with which it is in contact is not affected by any chemical reaction with the mercury or of such a nature that the mercury will form an amalgam therewith. In other words, the'members I and 2 associated with each other so as to form the chamber 3 between them, must be of material which will not chemically react to mercury and, furthermore, must be of a substance which is not wetted by the mercury, which latter situation might cause the mercury to spread out instead of maintaining its globular form.

The chamber should be filled with a gas that is inert to the component parts of the switch, as for example helium or hydrogen.

With the foregoing in mind, the member I may conveniently be made of a plastic or molded Bakelite or any other suitable substance. The member 2 may be made of a metal which will not chemically affect the mercury or will not form an amalgam therewith, or the surface of which metal will not be wetted by the mercury. If the member 2 be made of steel it may be advantageous to coat the inner surface thereon with tungsten or some similar substance which chemically has no aflinity toward mercury. While in the foregoing it has been mentioned that the member 2 may be made of metal, it will also be understood that it may be made of other material, such as a plastic, which may be formed in the manner indicated in Fig. 2 and which has the inherent resiliency to be moved to such a position as shown in Fig. 3 and returned to its initial position when the applied force is withdrawn.

The terminal members 5 may be made of a metal which is not chemically reactive to the mercury or would form an amalgam therewith and which, at the same time, will have the desired degree of conductivity. One form in which these terminals may be made is to employ copper or brass which are good electrical conductors and coat the same with tungsten or some other metal which is inert toward mercury.

From an inspection of Figs. 2 and 3 it will be seen that when the member 2, or at least, the central portion thereof, is moved by the application of a force thereto it will flex inwardly thereby diminishing the volumetric capacity of the chamber in which the mercury is located and deform the globule of mercury, as it were, flattening the same which will cause the mercury to spread outwardly without losing its discrete character and into contact with the terminal members 5 and 5a which will thus provide a situation in which the mercury forms a path for an electric current between the terminals 5 and 50. Release of the force applied permits the mercury to assume its initial position and disestablish the electrical connection.

It will be apparent that even if the switch as shown in Figs. 2 and 3 were vertically arranged and the globule of mercury due to gravity were displaced from the position which is shown in Fig. 2, nevertheless, when force were applied to the member 2 as indicated in Fig. 3 the spread of the mercury would be the same as that which is illustrated in Fig. 3.

The size of the chamber 3 and the volume of the globule of mercury placed within the chamber will vary, where the switch is intended for use in circuits of different ampere ratings. If the switch must take care of heavy amperage, of necessity the body of mercury must be larger than in the case where the switch is intended to take care of circuits of low amperage.

In Fig. 5 there is shown an adaptation of the same principle of operation in which the switch may be properly described as normally closed but effective to be moved to open position by force applied to move the movable member of the switch, as will now be described.

In the form shown in Fig. 5 the member la. carries terminal members 5c and 5d which occupy suitable openings in the member I in essentially the same manner as that described with Fig. 2.

Themember 2a is in all essential respects similar to the member 2 as shown in Fig. 2. In the particular construction shown these members I and '2 when assembled are mounted within a housing 8, which housing is provided with means for receiving and holding the associated members I and 2. In the construction thus described there is provided a packing member which is generally indicated at 9 which seals the chamber II] for purposes which will be later referred to.

In the normal position of the member 2a the central portion is biased toward the member Ia so that the body of mercury contained therein is flattened and spread out to be in contact with the terminals 5c and 5d and thus establish a path for an electric current between the aforementioned terminals. Referring to Fig. 6 it may be assumed that a negative force has been applied to the member 2a, such, for instance, as a subnormal pressure or vacuum which will move the central portion of the member 2a in an outward direction with respect to the member Ia.

This situation due to the inherent characteristic of the mercury will cause the mercury to form itself into a globule 1. Obviously, when the subnormal pressure or vacuum is removed then the member 2a will return to the position shown in Fig. 6.

The particular description or illustration which has just been given employing a subnormal pressure or vacuum is merely illustrative of any force that might be applied to move the diaphragmlike member 2a from the position shown in Fig.

6 from what may be termed its electrically closed position shown in Fig. 5 to the electrically open position shown in Fig. 6.

It will be apparent that the general assembly of elements such as shown in Figs. 5 and 6 may be similarly employed where the member 2a, is initially biased to an outward position that is similar to the situation shown in Fig. 1 so that the member 2a may be moved by the applica tion of a positive fluid pressure against the said member to move it to a position similar to that shown in Fig. 2 of the drawing. Such a construction could be used in connection with an automobile brake-applying system of the fluid type wherein a. switch such as that which is previously described might be used for operation of a stop light. The device described above may be mounted to communicate with a fluid conduit so that the member 2a would be subject to pressure when there is application of force to the brake pedal for the purpose of setting the brakes. The foregoing reference to a specific use is not intended to be in any way a limitation upon the usefulness of the invention herein set forth as obviously the herein described switch is of such characteristics or embodies a construction and characteristics which fit it for use under many and varied circumstances.

Having thus described my invention, I claim:

1. An electric switch comprising two cooperat ing members, the members being so related as to provide a closed chamber between them, a discrete globule of mercury within the chamber and of lesser volume than the chamber, electric circuit terminals operatively associated with said members and communicating with said chamber, one of the members having a portion adapted for movement toward and away from the other member, said portion when positioned toward the said other member will engage and deform the globule of mercury without destroying its discrete character thereby to contact both said terminals and establish electrical connection between said terminals and when in position away from said other member permits the body of mercury to assume its initial position and thereby disestablish electrical connection between said terminals.

2. An electric switch comprising two cooperating members, the members being so related as to provide a closed chamber between them, a discrete globule of mercury within the chamber and of lesser volume than the chamber, electric circuit terminals operatively associated with said.

members and communicating with said chamber, one of said members having a portion which is flexible and may be biased toward or away from the other of said members, said portion when biased toward the other member engaging and deforming the globule of mercury without -destroying its discrete character, to thereby contact both said terminals and establish electrical connectionbetween said terminals, and when biased away from said other member permits the body of mercury to assume its initial position and thereby prevent electrical connection between said terminals.

3. An electric switch comprising two cooperating members, the members being so related as to provide a closed chamber between them, a discrete globule of. mercury within the chamber and of lesser volume than the chamber, electric circuit terminals operatively associated with said members and communicating with said chamber, one of the members having a flexible portion which is normally biased away from the other of said members, means for moving said flexible portion toward the other member thereby to engage and deform the globule of mercury without destroying its discrete character and establish electrical connection between said terminals.

4. An electric switch comprising two cooperating members, the members being so related as to provide a closed chamber between them. a discrete globule of mercury within the chamber and of lesser volume than the chamber, electric circuit terminals associated with one of saidmembers said terminals being normally out of contact with the mercury, one of the said members having a portion adjacent the globule of mercury adapted for movement toward the other of said members whereby said movement will deform, by spreading out, the globule of mercury without destroying its discrete character and thereby establish electrical connection between said terminals.

5. An electric switch comprising a body having a closed chamber, electric circuit terminals operatively associated with said chamber, a discrete globule of mercury in said chamber of lesser volume than the chamber, movable means operatively associated with said body, adapted in one position to engage the globule of mercury to spread it out without destroying its discrete character, thereby to establish electrical connection between the terminals, and in another position of said movable means to permit the mercury to resume its original position and disestablish the electrical connection.

a body having a. An electric switch comprising spaced electric circuit tera closed chamber, minals communicating with said chamber, a discrete globule of mercuryinsaidchambcrof lesservolumethantbechembenwhichelobulo is spacedfrom the peripheral portions of the chamber whenthe switch is electrically open, means operatively associated with said body adapted in one position to engage the globule of mercury to spread it out without destroying its discrete character, thereby to establish electrical connection between the terminals and in another position of said movable member to permit the mercury to resume its original position and disestablish the electrical connection between the terminals.

7. An electric switch comprising a body having a closed chamber, the depth of the chamber diminishing from the center toward the periphery thereof, spaced electric circuit terminals communicating with said chamber, a discrete globule of mercury in said chamber of lesser volume than the chamber, which globule is spaced from the peripheral portions of the chamber when the switch is electrically open, means operatively associated with said body adapted in one position to engage the globule of mercury to spread it out without destroying its discrete character, thereby to establish electrical connection between the terminals and in another position of said movable member to permit the mercury to resunifglts original position and disestablish the electrical connection between the terminals.

8. An electric switch comprising two cooperating members, one of the members having a dished surface, the other of said members cooperating with the first-mentioned member to form a closed chamber, the depth of the chamber decreasing frorn, the central portion to the periphery thereof, ii'aced electric circuit terminals communicating with said chamber, a discrete globule of mercury in said chamber of lesser volume than the chamber, which globule is spaced from the peripheral portions of the chamber when the switch is electrically open, the second of the members first mentioned having a portion thereof which is adapted to be moved to engage the globule of mercury to spread it out without destroying its discrete character, thereby to es- .tablish electrical connection between the terminals, the said movable portion in another position permitting the mercury to resume its original position and disestablish the electrical connection between the terminals.

9. An electric switch comprising two cooperating members, the members being so related as to provide a closed chamber between them, one of said members having a portion at least which is flexible, the depth of the chamber decreasing from the central portion to the periphery thereof, spaced electric circuit terminals communicating with said chamber, a discrete globule of mercury in said chamber of lesser volume than the chamber, which globule is spaced from the peripheral portions of the chamber when the switch is electrically open, the flexible portion of the aforesaid member being movable to engage the globule of mercury to spread it out without destroying its discrete character, thereby to establish electrical connection between the terminals and said member in its non-flexed position permitting the mercury to resume its original position and disestablish the electrical connection between the terminals.

RALPH K. BOYER.

No references cited. 

